Backflow prevention device for high-pressure water injection wellhead

The utility model discloses a high-pressure water injection wellhead anti-backflow device which comprises a valve body, a connector is installed on the upper portion of the valve body, a connecting sleeve head is arranged on the outer side of the connector in a sleeved mode, a water inlet pipe is communicated with the upper portion of the connecting sleeve head, and an anti-backflow mechanism capable of automatically blocking a water injection opening after water injection is completed is arranged on the inner side of the valve body. By means of the backflow prevention mechanism, after water injection work of a well mouth is completed, the movable block and the valve plug can be matched with the springback force storage effect of the spring on the outer side below the telescopic sleeve rod to jack up through reverse screwing and dismounting of the connecting sleeve head and the effect that water pressure of a water inlet of the valve body disappears. Compared with the prior art, the valve plug made of the sta